The present invention relates generally to the storage and treatment of animal wastes generated at facilities where animals such as hogs or cattle are raised. More particularly, the invention relates to a microbial process for treating organic waste materials in waste holding facilities in order to reduce the sulfide content and enhance efficient degradation of the waste without significant odor.
The raising of large numbers of animals such as hogs and cattle for human consumption leads to the production of large amounts of organic waste materials. Typically, the organic waste material is collected and maintained in animal waste holding facilities, pits, or lagoons. Theoretically, bacteria in the waste materials work in concert to degrade organic matter over time.
Stresses placed on the ecology of the facility, including overloading of organic matter, changes in pH, temperature, and the like, disturb the ecology of the facility. Sulfide-producing bacteria dominate in a stressed facility, producing sulfides that are toxic to the growth and degradation activities of microorganisms. This results in a system that is inefficient in degrading wastes and continues to produce large amounts of hydrogen sulfides, volatile fatty acids, ammonia, and other malodorous compounds that create an unhealthy biomass in the waste facility.
Attempts to add organic digesting bacteria to a stressed, sulfide-rich facility have had limited success, due to the unfavorable conditions for their growth. Sulfur-degrading bacteria have been used to oxidize sulfides in some systems, but the effect is short-lived and fails to completely detoxify the facility and/or degrade organic matter.
There is a need and demand for a process for treating animal waste in a holding facility to create a healthy biomass to efficiently degrade organic waste and control solids build-up without toxicity and importantly, without the odors caused by sulfides, ammonia, and volatile fatty acids.
The present invention provides a process for the treatment of large amounts of organic waste in a holding facility, which process reduces sulfide levels to that which are non-toxic to organic digesting bacteria. The process provides an appropriate microbial environment and enhances efficient degradation of large amounts of organic wastes without toxicity, organic matter build up, and without odors caused by sulfides, ammonia, and volatile fatty acids.
The process of the invention includes administering to an animal a probiotic material capable of promoting organic digestion and maintaining a sulfide gas concentration of less than 10 ppm from a waste produced by the animal. The process of the invention also includes administering a probiotic material, capable of promoting organic digestion, to an animal and adding an innoculum of sulfide-utilizing bacteria to the waste produced by the animal. The process of the invention further includes administering to an animal a probiotic feed that includes organic digesting bacteria and lytic enzymes. Then an innoculum comprising sulfide-utilizing bacteria is added to a waste produced by the animal. The process of the invention further includes administering to an animal a probiotic feed additive that includes organic digesting bacteria and lytic enzymes. Then an innoculum comprising sulfide-utilizing bacteria is added to a waste produced by the animal. The invention further includes a probiotic feed additive composition.
For the purposes of understanding the invention, reference is now made to the preferred embodiments. No limitation of scope is intended by this description.
The following terms have the described definition for purposes of this invention:
xe2x80x9cWaste holding facilityxe2x80x9dxe2x80x94A facility for the holding, storage, and treatment of organic wastes, particularly animal waste, such as a pit or lagoon. This term also encompasses organic waste from sources other than animals, such as for example, plant waste and the like. The facility is exemplified by those found in large animal farms such as those raising hogs or cattle.
xe2x80x9cTreatingxe2x80x9dxe2x80x94Treating means inoculating organic waste and/or the animal with a bacteria and/or enzymes designed to enhance efficient degradation of organic matter with reduced odors. This team also encompasses the addition of probiotic material to the animal.
xe2x80x9cSulfide-rich organic wastexe2x80x9d is defined as malodorous animal waste harboring sulfide compounds, which waste is beneficially treated by the process of the invention. In general, the filtered sulfide content of the sulfide-rich animal waste ranges from about 1 mg/l to about 150 mg/l or greater. This term also encompasses organic waste from sources other than animals, such as for example, plant waste and the like. xe2x80x9cInnoculumxe2x80x9dxe2x80x94One or more bacteria, enzymes, yucca schidigera, ferrous chloride and oxidizing agents such as, for example, oxygen, halogen gases and the like, added to the organic waste material in the waste facility. The innoculum may be dried or fluid, mixed with a carrier or medium, and may include one or a mixture of bacteria, enzymes, yucca schidigera, ferrous chloride and oxidizing agents.
xe2x80x9cSulfide-utilizing bacteriaxe2x80x9dxe2x80x94Bacteria capable of utilizing sulfide, which may be anaerobic, aerobic, or facultative. Preferred is a consortium of sulfide-utilizing bacteria that includes bacteria which oxidize sulfide compounds. Most preferred is a consortium that includes bacteria capable of internalizing sulfur. Examples of useful sulfide-utilizing bacteria are found, for example, in Bergy""s Manual, and include species of Purple Non-Sulfur Bacteria (e.g., Rhodospirillium), Chromatianeae (e.g., Chromatium), Green Sulfur Bacteria (e.g., Chlorobium), Colorless Sulfur Bacteria (e.g., Thiobacaterium), and Filamentous Green bacteria (e.g., Chloroflexus). A preferred mixture of sulfide-utilizing bacteria including Rhodospirillium, Chromatium and Thiobacillus is commercially available from Syneco Systems, Inc. (St. Louis Pk, Minn.) under the trade name Persnickety Brand 713(trademark).
xe2x80x9cLowered-sulfide wastexe2x80x9dxe2x80x94A lowered-sulfide waste of the invention is a waste treated with sulfide-utilizing bacteria to decrease the content of sulfides. In general, a lowered-sulfide waste is a treated waste capable of sustaining growth and activity of organic digesting bacteria. The filtered sulfide content of the lowered-sulfide waste can range from about 0.5 mg/l or less to about 5 mg/l or less. It is appreciated that the lower the content of sulfide in the waste, the more efficient the organic digesting bacteria.
xe2x80x9cFiltered sulfidexe2x80x9dxe2x80x94The filtered sulfide content of animal waste in an animal waste facility is determined using standard methods and analysis, for example method EPA 375.4. In general, a sample of the waste slurry is filtered to remove solids, and the filtrate is analyzed for sulfide content. In general, the filtered sulfide content of a sample is about 30-40% of the sample""s measured solids sulfide content.
xe2x80x9cOrganic digesting microorganismsxe2x80x9dxe2x80x94Organic digesting microorganisms of the present invention are those bacteria, yeast, and fungi, which degrade organic matter commonly found in animal wastes. The organic digesting bacteria may be aerobic, anaerobic, or facultative. Preferably, the organic digesting bacteria of the invention produce lytic enzymes such as proteases, lipases, hemicelluases, cellulases, esterases, xylanase, urease, phytase and amylases that degrade organic matter. Also preferred are bacteria that utilize ammonia and volatile fatty acids. Useful organic digesting bacteria include species of Bacillus, Clostridium, and Deinococcus. Particularly useful is a consortium of bacteria capable of a variety of degradation activities. For example, a commercial mixture of organic digesting bacteria including licheniformis, pumilus, subtilus, amyloliquefaciens and megaterium provided with a mixture of lytic enzymes from Athea Labs (Milwaukee, Wis.) under the trade name Digestase 900(trademark) is particularly useful.
xe2x80x9cLytic enzymesxe2x80x9dxe2x80x94Herein, lytic enzymes are defined as those enzymes capable of degrading organic matter typically found in animal waste facility. Useful lytic enzymes include proteases, lipases, cellulases, hemicelluases, phytases and amylases. A preferred mixture of lytic enzymes is commercially available with a mixture of organic digesting bacteria as described above from Athea Labs under the trade name Digestase 900(trademark).
xe2x80x9cCirculatingxe2x80x9dxe2x80x94As used in this invention, circulating means to cause the contents of the animal waste facility to circulate, or to be stirred up. Conventional methods for circulating the contents of an animal waste facility include rotating blades or paddles, and aeration systems. A preferred method of circulation uses a commercial diffused air system to circulate the contents of the facility with compressed air (oxygen).
xe2x80x9cProbiotic Mixxe2x80x9d or xe2x80x9cProbiotic Materialxe2x80x9dxe2x80x94Herein, probiotic is defined as promoting growth of microflora and organic digestion. The probiotic mix or material of the invention contains organic digesting microorganisms, preferably bacteria. Preferred organic digesting microorganisms are lactobacillus, bacillus, bifidobacterium, streptococcus, yeast, fungus and the like. Probiotic mix or material may also include lytic enzymes such as, proteases, lipases, cellulases, hemicelluases, phytases, amylases and the like. Probiotic mix or material may also include yucca schidigera and oligosaccharides.
The method of the invention treats a malodorous animal waste facility to reduce or eliminate odors and to produce an efficient system for degrading organic matter. The facility is treated to lower the sulfide content, and to enhance the growth conditions for organic digesting bacteria. In general, a facility where the filtered sulfide content measures 1 mg/l or greater is malodorous and inefficient in degrading organic matter. In order to rapidly reduce odor and convert the environment of the waste facility to conditions for efficient waste degradation, the process of the invention lowers the sulfide content. Organic digesting bacteria and enzymes are added at a time when the facility can efficiently utilize them to degrade organic waste.
The bacterial innoculum may be added to the waste material in the waste holding facility as a dry powder (e.g., lyophilized, active bacteria), in liquid suspension, in a sol or gel in a bolus, or encapsulated, or in any convenient dispensing medium.
Probiotic material may be administered to the animal in an amount effective to promote healthy gut microflora and increase organic digestion. This probiotic material can be provided to the animal by known methods, including orally. Administration provides the probiotic material to the animal""s gastrointestinal tract to promote healthy gut microflora and improve organic material digestion.
Typically, probiotic material is introduced into the animal""s gastrointestinal tract via a feed additive that is added to the animal""s feed diet. Alternative methods of administration are liquid ingestion, paste or gel ingestion, boles, powder dusting surface of animal and the like. In addition to probiotic material, the feed additive may include, for example, carrier materials such as, limestone and wheat midds. The feed additive can be added to the animal""s regular diet at a rate of 0.01 to 10 and preferably about 0.5 to 2.5 pounds of additive per ton of animal feed.
The feed additive may contain about 0.3% to about 20% by weight of probiotic material (probiotic premix). Preferably the feed additive contains 7% to 15% by weight probiotic premix and most preferably about 10% to 13% by weight. Probiotic material includes lactobacillus, bacillus, bifidobacterium, streptococcus, yeast, enzymes, fungi, Yucca, oligosaccharides and the like. These can include one or more of the organisms shown below in Table 1A below.
When present in the feed or feed additive, probiotic enzymes may include lytic enzymes for digesting organic matter. Preferred lytic enzymes are proteases, lipases, hemicelluases, cellulases, esterases, xylanase, urease, phytase, amylases, and the like. The preferred enzymes or mixtures thereof are selected to aid in the digestion of the particular waste to be treated and on the diet of the animal.
Typically protease is present in the probiotic feed in an amount of 230-340 Protease Value (PV)/lb. In the feed additive, protease is typically present in an amount of 14,000-908,000 PV/lb and preferably 300,000-700,000 PV/lb and most preferably about 450,000 PV/lb.
Typically lipase is present in the probiotic feed in an amount of 55,000-82,000 United States Pharmacopoeia (USP)/lb. In the feed additive, lipase is typically present in an amount of 70-48,000 USP/gram and preferably 16,000 to 36,000 USP/gram and most preferably about 24,000 USP/gram.
Typically amylase is present in the probiotic feed in an amount of 6.8-10 Delft Value (DV)/lb. In the feed additive, amylase is typically present in an amount of 400-27,000 DV/lb and preferably 9,000 to 20,000 DV/lb and most preferably about 13,500 DV/lb.
Typically phytase is present in the probiotic feed in an amount of 100-550 Phytase Units (PU)/lb. In the feed additive, phytase is typically present in an amount of 5,000-1,000,000 PU/lb and preferably 50,000 to 800,000 PU/lb and most preferably about 200,000 PU/lb. Phytase also makes phosphorous in the feed more available to the animal.
Probiotic material such as organic digesting bacteria may be present in the basic feed diet in an amount of 1xc3x97102 CFU/gram to 1xc3x97107 CFU/gram and preferably 1xc3x97104 CFU/gram to 1xc3x97106 CFU/gram and most preferably about 7.5xc3x97105 CFU/gram. Organic digesting bacteria may be present in the feed additive in an amount of about 9.1xc3x97107 to 9.1xc3x971012 CFU/lb feed additive and preferably 9.1xc3x97109 to 9.1xc3x971011 CFU/lb feed additive and most preferably about 6.8xc3x971011 CFU/lb feed additive.
The probiotic yucca schidigera (yucca) can be optionally added to the probiotic feed additive. Yucca aids in lowering ammonia levels in the resulting organic waste. Yucca also stimulates probiotic material growth, particularly bacteria growth. The feed additive may contain about 0.3% to about 60% by weight of Yucca. Preferably the feed additive contains 4% to 30% by weight Yucca and most preferably about 13% by weight. Thus, yucca may be present in the feed additive in an amount of 10 to 1200 lbs/ton feed additive and preferably 80 to 600 lbs/ton of feed additive. Typically yucca can be present in the basic feed diet in an amount of 0.05 to 3.0 lbs/ton feed (2000 lbs feed) and preferably 0.1 to 1.5 lbs/ton feed.
Oligosaccharides is optionally added to the probiotic feed additive, such as, for example, sucrose, mannose, fructose, glucose, raffinose, stachyose, and verbascose oligosaccharides. These sugars stimulate gut microflora that aid in efficient organic digestion and odor reduction. Oligosaccharides can be present in the feed additive in the amount of 10% to 85% by weight and preferably 15% to 75% by weight and most preferably 60% by weight. Oligosaccharides may be added to the feed diet of the animals at a concentration of about 0.01% to about 1% by weight of the total feed. Thus, oligosaccharides may be present in the feed additive in an amount of 200 to 1700 lbs/ton feed additive and preferably 300 to 1500 lbs/ton of feed additive. Typically yucca can be present in the basic feed diet in an amount of 0.2 to 20 lbs/ton feed (2000 lbs feed) and preferably 1 to 2 lbs/ton feed.
A preferred probiotic premix for use in this invention, contains an equal mixture of three species of Bacillus: licheniformis, amyloliquidifaciens, and subtilis together with protease (10,000 PV units/g), amylase (300 DV units/g), lipase (2400 USP/mg) and is commercially available from Athea Labs, (Milwaukee, Wis.) under the trade name Digestase 900(trademark).
The remainder of the feed additive contains carrier materials like limestone and wheat midds.
To rapidly lower the sulfide content of the animal waste in the facility, and/or to maintain sulfide gas emissions from the waste to below 10 ppm and preferably below 1 ppm, the animal waste is inoculated with sulfide-utilizing bacteria. The amount of bacteria in the innoculum will vary with specific treatment conditions, including temperature, pH, and the like. In general, the innoculum is sufficient to deliver approximately 105-1010 sulfide-utilizing bacteria per ml of waste fluid, and preferably about 106-108 bacteria per ml. Also, alternate methods for reducing sulfide are available and can be used alone or in combination with the sulfide-utilizing bacteria innoculum such as, adding ferrous chloride and the like that chemically bind the sulfide in the waste or oxidize the sulfide in the waste.
The sulfide-utilizing bacterial innoculum can include one or more of the bacteria shown below in Table 1B. A preferred innoculum of sulfide-utilizing bacteria is commercially available from Syneco Systems, Inc. (St. Louis Park, Minn.) under the trade name Persnickety Brand 713(trademark).
The sulfide-utilizing bacteria in the inoculated facility is permitted to acclimate and to degrade sulfide compounds present in the facility. After a period of time sufficient to lower sulfide content and provide conditions for efficient growth and activity of organic digesting bacteria, organic digesting bacteria may be added to the facility. However, if a probiotic has been administered to the animal, adding organic digesting bacteria to the facility may not be necessary.
When used, the addition of organic digesting bacteria is preferably initiated when filtered sulfide content is less than 1 mg/l. Sufficient growth conditions to support some organic digesting bacterial growth can exist at higher filtered sulfide levels, for example, up to about 5 mg/l. It is generally understood that the organic digesting bacteria are more efficient at lower sulfide levels (e.g. less than 1 mg/l).
For a standard animal waste facility (about 1.5 million gallons of fluid waste) having an initial filtered sulfide content of about 1-150 mg/l, and a fluid waste temperature of about 70-75xc2x0 F., after a first innoculum of about 106-108 sulfide-utilizing bacteria per ml fluid waste, the filtered sulfide content is expected to decline to less than 1 mg/l in about 7 to 21 days. Under these conditions, to achieve a desirable efficiency of organic matter degradation without odors, the second innoculum (organic digesting bacteria) is preferably added about day 7-14. The time required to sufficiently reduce the sulfide level in the waste facility will vary according to factors including the condition of the facility at the time of treatment (such as initial sulfide content), composition of the organic matter, environmental conditions during treatment, (such as temperature and pH) and the like. In general, the sulfide-utilizing bacteria are most effective in lowering the sulfide content under conditions of neutral or near neutral pH (6.5-7.5) and warm temperatures (55-120xc2x0 F.). While the time interval between addition of the two bacterium will vary between 0 and about 21 days, preferably, the time interval will range between 3 and 21 days, and most preferably between 7-14 days.
As stated earlier, when a probiotic is administered to the animal, a second innoculum of organic digesting bacteria may not be necessary and is an optional process step. Organic digesting bacteria are considered probiotic.
When used, the second innoculum of organic digesting bacteria includes one or more species of Bacillus, Clostridium, and Deinococcus. Species of Bacillus are preferred. Most preferred is a consortium of organic digesting bacteria which is capable of digesting or utilizing a variety of organic compounds. Also preferred are those organic digesting bacteria that produce lytic enzymes capable of degrading organic compounds found in animal waste. The second innoculum optionally and preferably further includes lytic enzymes for digesting organic matter. Preferred lytic enzymes include proteases, lipases, cellulases, hemicelluases, phytases and amylases.
A most preferred innoculum for use in this second innoculum of the invention, contains an equal mixture of three species of Bacillus: licheniformis, amyloliquidifaciens, and subtilis together with protease (10,000 Protease Value (PV) units/g), amylase (300 Delft Value (DV) units/g), and lipase (2400 United States Pharmacopoeia (USP)/mg) and is commercially available from Athea Labs, (Milwaukee, Wis.) under the trade name Digestase 900(trademark).
In a deep pit barn, waste circulation is not generally recommended. Also, when a probiotic is administered to the animal, circulation of the pit material is not necessary. This is due to the fact that the organic digesting material is uniformly distributed throughout the pit material.
During the second innoculum, and continuing during the organic digesting phase of the treatment, it is preferred to circulate the fluid material of the facility in order to maximize the effect of the bacteria and enzymes. Circulation may be achieved by a number of known methods, including paddle, blade or fluid systems. A most preferred circulation system is a diffused air system placed in, and preferably at the bottom of the facility to produce a plume of air which rises to the surface to create a mixing action. Suitable air diffusion systems are commercially available, for example, from Clean Flow Laboratories (Plymouth, Min.). An aspirator-type system which causes circulation by injecting air at the surface of the facility is commercially available from Aeration Industries (Minneapolis, Minn.).
A useful diffuser system produces an output of about 10 cubic ft/minute (cfm) per surface acre of the facility. This is accomplished with a 10 psi, 10 cfm rotary vane compressor and two diffusers.
To maintain an animal waste facility capable of efficiently degrading large amounts of animal waste (e.g., amounts that would typically overload a non-treated facility""s degradation capacity) with reduced odor and reduced solids build-up, the sulfide-utilizing innoculum and organic digesting innoculum are periodically applied to the facility. However, when the probiotic is administered to the animals, the addition of additional organic digesting innoculum may not be necessary. The probiotic is typically fed to the animals on a regular, preferably, continuous basis.
The specific time interval between periodic applications of the process of the invention varies with the specific conditions of the facility: e.g., amount of new animal waste deposited, the size of the facility, the environmental conditions since last application, and the like. Generally, the lowered-sulfide waste sulfide gas emissions in the barn are maintained below about 10 ppm and preferably below about 1 ppm (time weighted average) based on OSHA method # ID-141. Lowered-sulfide waste ammonia gas emissions in the barn are maintained below about 35 ppm and preferably below about 5 ppm (time weighted average) based on OSHA method # ID-I 88.
In general, for most commercial facilities, the innoculum are applied at about monthly intervals to maintain a healthy biomass capable of degrading large amounts of animal waste in a shortened period of time as compared with a non-treated facility.
The combined use of a probiotic feed additive and a sulfide utilizing inoculation to the waste material provides synergistic benefits for animal production, especially swine production. As shown in Example 4, the use of a probiotic feed and sulfide utilizing inoculation reduces hydrogen sulfide and ammonia concentrations in the waste pit, barn and surrounding area. The following tables summarize the effects of hydrogen sulfide and ammonia at specific concentrations on both humans and swine. Reducing the concentration of these compounds at the waste facility is particularly health promoting for humans and animals. The following tables are taken from a 1995 publication by the Minnesota Department of Agriculture entitled xe2x80x9cManure Management Alternatives: A Supplemental Manualxe2x80x9d and illustrate the effect of hydrogen sulfide and ammonia on humans and swine are various concentrations.
The use of the combined treatment of the invention, a probiotic feed additive and sulfide utilizing inoculation reduces exposure to noxious and unhealthy volatile gases and results in increased feed efficiency and average daily weight gain. This combination also results in decreased back fat, respiratory infections, and decreased need for antibiotics. This combination also decreases the total solids in the waste pit, allowing the waste pit to be pumped out more easily than untreated waste pits having higher solids content.